Radio condition triggering of bitrate request for codec rate adaptation

ABSTRACT

A first user equipment (UE) device receives Packet Loss Rate (PLR) threshold configuration information from a base station that is serving the first UE device. The first UE device also receives a recommended bitrate from the base station. The recommended bitrate is to be used for a Voice over Long-Term Evolution (VoLTE) call or a Video over Long-Term Evolution (ViLTE) call between the first UE device and a second UE device. The first UE device determines the radio condition of the first UE device by measuring the PLR at the first UE device. If the measured PLR is below the lower PLR threshold value or above the upper PLR threshold value, the first UE device transmits a bitrate query to the base station.

CLAIM OF PRIORITY

The present application claims priority to Provisional Application No.62/454,469, entitled “TRIGGERING OF BITRATE REQUEST FOR CODEC RATEADAPTATION”, filed Feb. 3, 2017, assigned to the assignee hereof andhereby expressly incorporated by reference in its entirety.

FIELD

This invention generally relates to wireless communications and moreparticularly to rate adaptation in a radio access network.

BACKGROUND

3rd Generation Partnership Project (3GPP) specified a new voice codecnamed EVS (Enhanced Voice Services). A codec is a device or program that(1) encodes data for transmission and/or storage, and (2) decodesreceived data for playback, storage, and/or editing. EVS provides highvoice quality over a wide range of rates, which allows the low EVS codecrates to still have sufficient quality, and may be used in poor coverageenvironments and overload scenarios. However, it is still desirable touse the higher codec rates for enhanced audio quality whenever possible.EVS has the flexibility, with a wider rate range and full audiobandwidth, to deliver speech quality that matches other audio inputs,such as stored music, while offering high robustness to delay, jitter,and packet losses.

Radio conditions may also impact the codec mode and codec rate. Forexample, under poor radio conditions, a lower codec rate may be used toreduce the packet loss, whereas a higher codec rate can be used in goodradio conditions to ensure a better user experience. Therefore, aflexible and efficient codec modification mechanism is needed thataccounts for the voice codec, network capacity, radio conditions, anduser experience.

SUMMARY

A first user equipment (UE) device receives Packet Loss Rate (PLR)threshold configuration information from a base station that is servingthe first UE device. The first UE device also receives a recommendedbitrate from the base station. The recommended bitrate is to be used fora Voice over Long-Term Evolution (VoLTE) call or a Video over Long-TermEvolution (ViLTE) call between the first UE device and a second UEdevice. The first UE device determines the radio condition of the firstUE device by measuring the PLR at the first UE device. If the measuredPLR is below the lower PLR threshold value or above the upper PLRthreshold value, the first UE device transmits a bitrate query to thebase station.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a communication system for an example inwhich a change in the radio condition of a user equipment (UE) devicetriggers the UE device to transmit a bitrate query to a base station.

FIG. 2A is a block diagram of an example of the base stations shown inFIG.

FIG. 2B is a block diagram of an example of the UE devices shown in FIG.1.

FIG. 3 is a messaging diagram of an example in which a change in theradio condition of a user equipment (UE) device triggers the UE deviceto transmit a bitrate query to a base station.

FIG. 4 is a flowchart of an example of a method in which a change in theradio condition of a user equipment (UE) device triggers the UE deviceto transmit a bitrate query to a base station.

DETAILED DESCRIPTION

Voice-over-LTE (VoLTE) is a key feature for the 3GPP Long Term Evolution(LTE) communication specification to provide voice service and is beingdeployed and launched by operators all over the world, which makes VoLTEcapability extremely important for operators. One of the criticalfactors that may impact the user experience of VoLTE service is thevoice codec configuration. For example, a higher Adaptive Multi-Rate(AMR) voice code rate may provide a higher-definition voice call andaccordingly a better user experience. When a higher AMR voice code rateis used, the higher codec rate requires more radio resource allocation,which implies less available network capacity.

The base station (e.g., eNB) of the Radio Access Network (RAN) is in thebest position to trigger voice codec rate adaptation. Thus, aneNB-assisted (or RAN-assisted) codec rate adaptation solution should beconsidered. In order to support eNB-assisted codec rate adaptation, oneof the main questions to consider is if the eNB needs to have theinformation on the specific codec rates for each type of supportedcodec. If we assume the eNB has specific information about the codecrates, we should also consider if the eNB would also need to know thecodec type, the frame aggregation, the redundancy level, and theredundancy offset. This would imply the eNB could essentially serve asthe end point for codec rate adaptation in place of the user equipment(UE) device.

However, if the eNB only has the codec rate information, it is unclearhow much weight the UE device should give to the eNB's recommended codecrate as one of the inputs to the UE device's application layer. Notethat traditionally eNBs do not handle any application layer signaling.Rather, they only handle the Access Stratum (AS) part of the LTE system.Adding application layer signaling within the eNB would drasticallychange the existing paradigm of how the network architecture isstructured. Thus, the following examples describe techniques and systemconfigurations that enable the eNB to facilitate rate adaptation despitenot having codec rate information.

Moreover, as the UE device moves in and out of coverage, the eNB'sselection of a recommended rate for the UE device should be a functionof the UE device's radio condition and whether the recommended rate isapplicable to the UE device when the UE device is handed over to atarget eNB.

Although most of the examples discussed herein focus on VoLTEapplications, any of the following examples may be modified forVideo-over-LTE (ViLTE) applications.

FIG. 1 is a block diagram of a communication system for an example inwhich a change in the radio condition of a user equipment (UE) devicetriggers the UE device to transmit a bitrate query to a base station.The communication system 100 is part of a radio access network (notshown) that provides various wireless services to UE devices that arelocated within the respective service areas of the various base stationsthat are part of the radio access network. The base station 102 provideswireless services to UE device 106 via downlink signals 104.

In the interest of clarity and brevity, communication system 100 isshown as having only two base stations 102, 103. Initially, first basestation 102 provides wireless services to UE device 106, and second basestation 103 provides wireless services to UE device 108. However, inother examples, communication system 100 could have any suitable numberof base stations. Base stations 102, 103, which are sometimes referredto as an eNodeB or eNB, communicate with the wireless user equipment(UE) devices 106, 108 by transmitting downlink signals 104, 109 to theUE devices 106, 108, respectively. Base stations 102, 103 receive uplinksignals 116, 111 transmitted from the UE devices 106, 108, respectively.The UE devices 106, 108 are any wireless communication devices such asmobile phones, transceiver modems, personal digital assistants (PDAs),and tablets, for example.

Base stations 102, 103 are connected to the network through a backhaul(not shown) in accordance with known techniques. As shown in FIG. 2A,base station 102 comprises controller 204, transmitter 206, and receiver208, as well as other electronics, hardware, and code. Although FIG. 2Aspecifically depicts the circuitry and configuration of first basestation 102, the same base station circuitry and configuration isutilized for second base station 103. The base station 102 is any fixed,mobile, or portable equipment that performs the functions describedherein. The various functions and operations of the blocks describedwith reference to the base station 102 may be implemented in any numberof devices, circuits, or elements. Two or more of the functional blocksmay be integrated in a single device, and the functions described asperformed in any single device may be implemented over several devices.

For the example shown in FIG. 2A, the base station 102 may be a fixeddevice or apparatus that is installed at a particular location at thetime of system deployment. Examples of such equipment include fixed basestations or fixed transceiver stations. In some situations, the basestation 102 may be mobile equipment that is temporarily installed at aparticular location. Some examples of such equipment include mobiletransceiver stations that may include power generating equipment such aselectric generators, solar panels, and/or batteries. Larger and heavierversions of such equipment may be transported by trailer. In still othersituations, the base station 102 may be a portable device that is notfixed to any particular location. Accordingly, the base station 102 maybe a portable user device such as a UE device in some circumstances.

The controller 204 includes any combination of hardware, software,and/or firmware for executing the functions described herein as well asfacilitating the overall functionality of the base station 102. Anexample of a suitable controller 204 includes code running on amicroprocessor or processor arrangement connected to memory. Thetransmitter 206 includes electronics configured to transmit wirelesssignals. In some situations, the transmitter 206 may include multipletransmitters. The receiver 208 includes electronics configured toreceive wireless signals. In some situations, the receiver 208 mayinclude multiple receivers. The receiver 208 and transmitter 206 receiveand transmit signals, respectively, through an antenna 210. The antenna210 may include separate transmit and receive antennas. In somecircumstances, the antenna 210 may include multiple transmit and receiveantennas.

The transmitter 206 and receiver 208 in the example of FIG. 2A performradio frequency (RF) processing including modulation and demodulation.The receiver 208, therefore, may include components such as low noiseamplifiers (LNAs) and filters. The transmitter 206 may include filtersand amplifiers. Other components may include isolators, matchingcircuits, and other RF components. These components in combination orcooperation with other components perform the base station functions.The required components may depend on the particular functionalityrequired by the base station.

The transmitter 206 includes a modulator (not shown), and the receiver208 includes a demodulator (not shown). The modulator modulates thesignals to be transmitted as part of the downlink signals 104 and canapply any one of a plurality of modulation orders. The demodulatordemodulates any signals, including uplink signals 116, received at thebase station 102 in accordance with one of a plurality of modulationorders.

Returning to FIG. 1, the communication system 100 provides variouswireless services to the UE devices 106, 108 via base stations 102, 103,respectively. For the examples herein, the communication system 100operates in accordance with at least one revision of the 3rd GenerationPartnership Project Long Term Evolution (3GPP LTE) communicationspecification. A first UE device 106 receives downlink signal 104 viaantenna 212 and receiver 214, as shown in FIG. 2B. Although FIG. 2Bspecifically depicts the circuitry and configuration of first UE device106, the same UE device circuitry and configuration is utilized forsecond UE device 108. Besides antenna 212 and receiver 214, the first UEdevice 106 further comprises controller 216 and transmitter 218, as wellas other electronics, hardware, and code. The first UE device 106 is anyfixed, mobile, or portable equipment that performs the functionsdescribed herein. The various functions and operations of the blocksdescribed with reference to the first UE device 106 may be implementedin any number of devices, circuits, or elements. Two or more of thefunctional blocks may be integrated in a single device, and thefunctions described as performed in any single device may be implementedover several devices.

The controller 216 includes any combination of hardware, software,and/or firmware for executing the functions described herein as well asfacilitating the overall functionality of a UE device. An example of asuitable controller 216 includes code running on a microprocessor orprocessor arrangement connected to memory. The transmitter 218 includeselectronics configured to transmit wireless signals. In some situations,the transmitter 218 may include multiple transmitters. The receiver 214includes electronics configured to receive wireless signals. In somesituations, the receiver 214 may include multiple receivers. Thereceiver 214 and transmitter 218 receive and transmit signals,respectively, through antenna 212. The antenna 212 may include separatetransmit and receive antennas. In some circumstances, the antenna 212may include multiple transmit and receive antennas.

The transmitter 218 and receiver 214 in the example of FIG. 2B performradio frequency (RF) processing including modulation and demodulation.The receiver 214, therefore, may include components such as low noiseamplifiers (LNAs) and filters. The transmitter 218 may include filtersand amplifiers. Other components may include isolators, matchingcircuits, and other RF components. These components in combination orcooperation with other components perform the UE device functions. Therequired components may depend on the particular functionality requiredby the UE device.

The transmitter 218 includes a modulator (not shown), and the receiver214 includes a demodulator (not shown). The modulator can apply any oneof a plurality of modulation orders to modulate the signals to betransmitted as part of the uplink signals 116, which are shown inFIG. 1. The demodulator demodulates the downlink signals 104 inaccordance with one of a plurality of modulation orders.

In some of the examples described herein, it is assumed that basestations 102, 103 are agnostic to codec rate information, which meansthat the base stations 102, 103 are not aware of which bitrates matchwith the codec rates available to the UE devices 106, 108 in theapplication layer. Therefore, the base station 102 must be informedregarding which bitrates are appropriate to recommend to the UE device106; for purposes of rate adaptation, this is an important detail sincethe UE device 106 cannot autonomously decide which bitrate to usewithout permission from the base station 102.

In operation, one or more triggering events will cause a base station102 to determine a bitrate to recommend to the UE device 106. In someexamples, the base station 102 receives a bitrate query, which is arequest for an unspecified rate increase or decrease for a particularcommunication link (e.g., downlink 104 or uplink 116). In otherexamples, the bitrate query comprises a request for a specific rate,which may, in some cases, be based on a rate negotiation request from asecond UE device 108. If the base station 102 is codec rate agnostic,the bitrate query will be a request for a specific bitrate rather thanfor a specific codec rate.

The base station 102 utilizes controller 204 to determine a bitrate torecommend to the UE device 106. The recommended bitrate takes intoaccount, among other factors, any previously received bitrate query, theradio condition of the first UE device 106, and the current level ofnetwork congestion measured by the base station 102. Of course, anyother suitable criteria may be used by the base station 102 in selectinga recommended bitrate. In some cases, the recommended bitrate is abitrate supported by the base station 102. The bitrate recommendation,in some examples, is a recommendation for a higher rate. In otherexamples, the bitrate recommendation is a recommendation for a lowerrate.

After determining which bitrate to recommend to the UE device 106, thebase station 102 transmits, via transmitter 206 and antenna 210, therecommended bitrate to be used for a call between the first UE device106 and a second UE device 108. The call may be a Voice over Long-TermEvolution (VoLTE) call or a Video over Long-Term Evolution (ViLTE) call.The UE device 106 receives the recommended bitrate via antenna 212 andreceiver 214. The recommended bitrate is represented in FIG. 3 by signal304.

In addition to the recommended bitrate, the base station 102 transmitsPacket Loss Rate (PLR) threshold configuration information to the UEdevice 106, in some examples. The PLR threshold configurationinformation, which comprises a lower PLR threshold value and/or an upperPLR threshold value, may be transmitted with the recommended bitrate orin a separate transmission. The PLR threshold configuration informationis represented in FIG. 3 by signal 302. In other examples, theapplication layer of the UE device 106 configures the lower PLRthreshold and/or the upper PLR threshold by providing a lower PLRthreshold value and/or an upper PLR threshold value to the controller216 of the UE device 106, respectively.

The PLR is calculated at the application layer of the UE device 106 andreflects the packet errors for the application layer. Based on the PLR,the UE device 106 can determine whether the radio condition of the UEdevice 106 has changed sufficiently enough to require a change inbitrate. By specifying the particular PLR threshold values that shouldbe used by the UE device 106, the base station 102, or the applicationlayer of the UE device 106, configures the degree to which the radiocondition of the UE device 106 must change in order to trigger the UEdevice 106 to transmit a bitrate query to the base station 102.

In response to receiving the recommended bitrate from the base station102, the controller 216 of first UE device 106 determines whether to (1)implement (e.g., accept) the recommended bitrate, (2) reject therecommended bitrate, (3) request a different bitrate than therecommended bitrate, (4) negotiate the bitrate with second UE device108, or (5) perform any combination of two or more of the foregoingoptions. If the UE device 106 chooses to initiate a bitrate negotiationwith the second UE device 108 to determine a bitrate to be used for theVoLTE call between the first and second UE devices 106, 108, the firstUE device 106 and the second UE device 108 use their respectivetransmitters 218, controllers 216, and antennas 212 to negotiate thebitrate via the application layer. This bitrate negotiation occurs viacommunication link 112 in FIG. 1 and is represented in FIG. 3 byApplication Layer Signaling 306. The bitrate negotiation ApplicationLayer Signaling 306 may also depend on the PLR experienced at UE 108.

In other examples, the first UE device 106 may already know whichbitrate the second UE device 108 is capable of using for the VoLTE call,and thus, no negotiation is required. Once the bitrate negotiationbetween the first and second UE devices 106, 108 concludes, or isskipped, the first and second UE devices 106, 108 implement a bitratefor the VoLTE call, or the first UE device 106 may determine that abitrate query should be sent to the base station 102.

In determining whether to transmit a bitrate query, the UE device 106determines the radio condition of the UE device 106 by measuring the PLRat the UE device 106 and through the bitrate negotiation with UE device108. If the measured PLR is below the lower PLR threshold value, the UEdevice 106 may transmit a bitrate query to the base station 102. In someexamples, this bitrate query is a request to decrease the bitrate usedfor the downlink communication link 104. However, in some cases, the UEdevice 106 may be configured to refrain from sending this bitrate queryif the UE device 106 is already operating at the minimum Guaranteed BitRate (GBR).

If the measured PLR is above the upper PLR threshold value, the UEdevice 106 may transmit a bitrate query to the base station 102. In someexamples, this bitrate query is a request to increase the bitrate usedfor the downlink communication link 104. However, in some cases, the UEdevice 106 may be configured to refrain from sending this bitrate queryif the UE device 106 is already operating at the Maximum Bit Rate (MBR).

In addition to sending bitrate queries regarding the downlinkcommunication link 104, the UE device 106 is capable of sending bitratequeries regarding the uplink communication link 116, in some examples.In these examples, the UE device 106 determines whether to the send thebitrate query based on the radio condition of the uplink communicationlink 116. The UE device 106 determines the radio condition of the uplinkcommunication link 116 by the number of Hybrid Automatic Repeat Request(HARQ) retransmissions based on Acknowledgement (ACK) or Negative-ACK(NACK) signals received from the base station 102.

If the UE device 106 determines that a bitrate query should be sent tothe base station 102, the UE device 106 transmits, via transmitter 218and antenna 212, a bitrate query to the base station 102. The bitratequery can be a request for an unspecified rate increase or decrease orfor a specific rate, which may be an increase or a decrease from thecurrent rate or the recommended rate. In the examples in which the basestation 102 is codec rate agnostic, any specific rate request will be arequest for a specific bitrate rather than for a specific codec rate.

In addition to the rate request, the bitrate query may also include acause value, in some examples, which indicates the reason that the UEdevice 106 sent the bitrate query. For example, the cause value couldindicate that the bitrate query is being sent due to a change in radiocondition. More specifically, the cause value could represent any of thefollowing: “Radio Condition Change,” “Bad PLR,” “High PLR,” “Low PLR,”“Rate Negotiation Received from Peer UE Device,” or “About toRe-Negotiate Rate with Peer UE Device.” Of course, any other suitablecause values may be included in the bitrate query in order to assist thebase station 102 in determining what bitrate to recommend to the UEdevice 106.

In other examples, the bitrate query may also include a direction of thebitrate query. For example, the bitrate query could include a requestfor a higher (or lower) rate than (1) a currently configured bitrate, or(2) the rate that was recommended by the base station 102 (e.g., signal304 in FIG. 3). However, the bitrate query would not request a specificrate, in these examples.

In still other examples, the bitrate query may include a cause value, asmentioned above, and a request for a specific bitrate. The combinationof the cause value and the specific bitrate indicate the direction ofthe bitrate query (e.g., whether the request is for a rate increase ordecrease). For example, the bitrate query would include the cause valueand a request for a specific rate that is higher (or lower) than (1) acurrently configured bitrate, or (2) the rate that was recommended bythe base station 102.

In further examples, the bitrate query may also include the measuredPLR. In still further examples, the bitrate query may also include anindicator of the severity of the change in radio condition (e.g.,“high,” “medium,” or “low) that triggered the UE device 106 to transmitthe bitrate query. The base station 102 can utilize the measured PLRand/or the indicator of the severity of the change in radio condition todetermine whether to recommend a large or a small change in the bitratein order to address the change in radio condition.

Regardless of the exact contents of the bitrate query, the UE device 106transmits, via transmitter 218 and antenna 212, the bitrate query to thebase station 102. The base station 102 receives the bitrate query viaantenna 210 and receiver 208. The bitrate query is represented in FIG. 3by signal 308. Upon receipt of the bitrate query, the base station 102will make a bitrate recommendation based on any number of factors,including one or more of the following: the bitrate query received fromthe UE device 106, the radio condition of the UE device 106, and thecurrent level of network congestion measured by the base station 102. Ofcourse, any other suitable factors could be considered by the basestation 102 in determining which bitrate to recommend.

FIG. 3 is a messaging diagram of an example in which a change in theradio condition of a user equipment (UE) device triggers the UE deviceto transmit a bitrate query to a base station. In this example, the basestation 102 transmits Packet Loss Rate (PLR) threshold configurationinformation to the UE device 106. The PLR threshold configurationinformation, which comprises a lower PLR threshold value and/or an upperPLR threshold value, may be transmitted with the recommended bitrate orin a separate transmission. The PLR threshold configuration informationis represented in FIG. 3 by signal 302. In other examples, theapplication layer of the UE device 106 configures the lower PLRthreshold and/or the upper PLR threshold by providing a lower PLRthreshold value and/or an upper PLR threshold value to the controller216 of the UE device 106, respectively.

The base station 102 determines a recommended bitrate based on anynumber of suitable factors. After determining which bitrate to recommendto the UE device 106, the base station 102 transmits a recommendedbitrate to be used for a Voice over Long-Term Evolution (VoLTE) call ora Video over Long-Term Evolution (ViLTE) call between the first UEdevice 106 and a second UE device 108. The recommended bitrate isrepresented in FIG. 3 by signal 304. As mentioned above, the recommendedbitrate may be transmitted with the PLR threshold configurationinformation or may be transmitted in a separate transmission, as shownin FIG. 3.

After receiving the recommended bitrate, the UE device 106 may elect toinitiate a bitrate negotiation with the second UE device 108 todetermine a bitrate to be used for the call between the first and secondUE devices 106, 108. This bitrate negotiation, if it occurs, isrepresented in FIG. 3 by Application Layer Signaling 306. Afterconducting, or skipping, the rate negotiation, the first UE device 106implements a bitrate for the call or determines that a bitrate queryshould be sent to the base station 102.

In the example shown in FIG. 3, the UE device 106 determines that abitrate query should be sent to the base station 102 due to a change inthe radio condition of the UE device 106. The UE device 106 transmits abitrate query to the base station 102. The bitrate query is representedin FIG. 3 by signal 308. As described above, the bitrate query may be arequest for an unspecified rate increase or decrease. In other examples,the bitrate query is a request for a specific bitrate. In still otherexamples, the bitrate query may include a cause value, a direction ofthe bitrate query, the measured PLR, and/or an indicator of the severityof the change in radio condition of the UE device 106.

FIG. 4 is a flowchart of an example of a method in which a change in theradio condition of a user equipment (UE) device triggers the UE deviceto transmit a bitrate query to a base station. The steps of method 400may be performed in a different order than described herein and shown inthe example of FIG. 4. Furthermore, in some examples, one or more of thesteps may be omitted. Moreover, in other examples, one or moreadditional steps may be added.

In the example shown in FIG. 4, the method 400 begins at step 402, inwhich UE device 106 receives PLR threshold configuration informationfrom a base station 102 that is serving the UE device 106. As mentionedabove, the PLR threshold configuration information comprises a lower PLRthreshold value and/or an upper PLR threshold value. In other examples,the application layer of the UE device 106 provides the PLR thresholdvalues to the controller 216 of the UE device 106.

At step 404, the UE device 106 receives a recommended bitrate from thebase station 102. The recommended bitrate is to be used for a callbetween the first UE device 106 and the second UE device 108. The callcan be a Voice over Long-Term Evolution (VoLTE) call or a Video overLong-Term Evolution (ViLTE) call.

At step 406, the UE device 106 determines the radio condition of the UEdevice 106 by measuring the PLR at the UE device 106.

At step 408, if the UE device 106 determines that the measured PLR isbelow the lower PLR threshold value or above the upper PLR thresholdvalue, the UE device 106 transmits a bitrate query to the base station102. As described above, the bitrate query may be a request for anunspecified rate increase or decrease. In other examples, the bitratequery is a request for a specific bitrate. In still other examples, thebitrate query may include a cause value, a direction of the bitratequery, the measured PLR, and/or an indicator of the severity of thechange in radio condition of the UE device 106.

Clearly, other embodiments and modifications of this invention willoccur readily to those of ordinary skill in the art in view of theseteachings. The above description is illustrative and not restrictive.This invention is to be limited only by the following claims, whichinclude all such embodiments and modifications when viewed inconjunction with the above specification and accompanying drawings. Thescope of the invention should, therefore, be determined not withreference to the above description, but instead should be determinedwith reference to the appended claims along with their full scope ofequivalents.

1. A method comprising: receiving, at a first user equipment (UE)device, a recommended bitrate from a base station serving the first UEdevice, the recommended bitrate to be used for a call between the firstUE device and a second UE device, the call being either a Voice overLong-Term Evolution (VoLTE) call or a Video over Long-Term Evolution(ViLTE) call; determining a radio condition of the first UE device bymeasuring a Packet Loss Rate (PLR) at the first UE device; and if themeasured PLR is below a lower PLR threshold value or is above an upperPLR threshold value, transmitting a bitrate query to the base station.2. The method of claim 1, wherein the bitrate query includes a causevalue that indicates a reason for the bitrate query.
 3. The method ofclaim 2, wherein the cause value is an indication of a change in theradio condition of the first UE device.
 4. The method of claim 1,wherein the bitrate query includes a direction of a requested bitratechange.
 5. The method of claim 4, wherein a bitrate increase isdetermined by the inclusion of a bitrate value in the bitrate query thatexceeds a currently configured bitrate value.
 6. The method of claim 4,wherein a bitrate decrease is determined by the inclusion of a bitratevalue in the bitrate query that is below a currently configured bitratevalue.
 7. The method of claim 1, wherein the bitrate query includes themeasured PLR.
 8. The method of claim 1, further comprising: configuring,by the base station, the lower PLR threshold value and the upper PLRthreshold value.
 9. The method of claim 1, further comprising:configuring, by an application layer of the first UE device, the lowerPLR threshold value and the upper PLR threshold value.
 10. A systemcomprising: a base station; and a first user equipment (UE) device beingserved by the base station, the first UE device comprising: a receiverconfigured to: receive a recommended bitrate from the base station, therecommended bitrate to be used for a call between the first UE deviceand a second UE device, the call being either a Voice over Long-TermEvolution (VoLTE) call or a Video over Long-Term Evolution (ViLTE) call,a controller coupled to the receiver, the controller configured to:determine a radio condition of the first UE device by measuring a PacketLoss Rate (PLR) at the first UE device, and a transmitter coupled to thecontroller, the transmitter configured to: transmit a bitrate query tothe base station, if the measured PLR is below a lower PLR thresholdvalue or is above an upper PLR threshold value.
 11. The system of claim10, wherein the bitrate query includes a cause value that indicates areason for the bitrate query.
 12. The system of claim 11, wherein thecause value is an indication of a change in the radio condition of thefirst UE device.
 13. The system of claim 10, wherein the bitrate queryincludes a direction of a requested bitrate change.
 14. The system ofclaim 13, wherein a bitrate increase is determined by the inclusion of abitrate value in the bitrate query that exceeds a currently configuredbitrate value.
 15. The system of claim 13, wherein a bitrate decrease isdetermined by the inclusion of a bitrate value in the bitrate query thatis below a currently configured bitrate value.
 16. The system of claim10, wherein the bitrate query includes the measured PLR.
 17. The systemof claim 10, wherein the base station further comprises: a transmitterconfigured to transmit a lower PLR threshold value and an upper PLRthreshold value to the first UE device.
 18. The system of claim 10,wherein the controller of the first UE device is further configured to:receive, from an application layer of the first UE device, a lower PLRthreshold value and an upper PLR threshold value.